Means for controlling the firing of a gun against a movable target

ABSTRACT

This invention provides a method of and a device for controlling the firing of a gun equipped with a sighting telescope which, by taking due consideration for the chief parameters, permit of introducing the correction required for firing against a moving target. This correction is obtained by moving the cross-hairs of the sighting telescope which is responsive to servo-means and adapted to travel through an angular distance equal to Omega T in the direction opposite to the pursuit direction. This value Omega T is mainly subordinate to the distance and to the speed Omega of the target which determine the gun pursuit speed and also to the time T of the shell or projectile course. The correction may be introduced according to two different methods: in the first method, the position of the cross-hairs of the sighting telescope is acted upon continuously, and in the second method requiring the use of a fixed pair of cross-hairs and of a movable pair of cross-hairs the correction is introduced only at the last moment on the firer&#39;&#39;s will, when the pursuit is stabilized.

States m m Maxime et al. [4 Apr. 17, 1973 4] MEANS FOR CONTROLLWG THE 2,660,794 12 1953 06cm et al ..33/49.3

IR F A GUN A A A 3,059,338 10/1962 Coeytaux 3,508,335 4/1970 Sundstrom ..33/49 Inventors: Jacques Maxime; Rene Larribaut, Primary Examiner stephen C. Bentley both of Tarbes Attorney-Robert E. Burns and Emmanuel J. Lobato France [73] Assignee: French State, represented by the [57] ABSTRACT Minister of Armed Forces, Ministeri- This invention provides a method of and a device for a] Delegation for Weapons, T h icontrolling the firing of a gun equipped with a sighting ca] Direction f Land weapons telescope which, by taking due consideration for the M f t i workshop, Tarbes, chief parameters, permit of introducing the correction p France required for firing against a moving target. This correction is obtained by moving the cross-hairs of the [22] Filed: 1969 sighting telescope which is responsive to servo-means [21] APP] NOJ 817,624 and adapted to travel through an angular distance equal to QT in the direction opposite to the pursuit direction. This value QT is mainly subordinate to the Foreign Application y Data distance and to the speed 0. of the target which deter- Apr 25, 1968 France 68l49397 mine the gun i i Speed and to time T of the shell or pro ectile course. The correction may be introduced according to two different methods: in the (5|. ..89/41 E, 33/2?F8i135g/(2)g first method the position of the crossmairs of the 58 F- "i; .2 g telescope is acted upon continuously, and in 1 0 can 9/ the second method requiring the use of a fixed pair of 89/4152 33/492 237v 239; cross-hairs and of a movable pair of cross-hairs the 235/615; 356/29 252 correction is introduced only at the last moment on [56] R f C ed the firers will, when the pursuit is stabilized.

e erences it 3 Claims, 2 Drawing Figures UNITED STATES PATENTS 2,464,195 3/1949 Hurley et a]. 33/49.3 X

SYNCHO-GENERATOR 13 REDUCING EAR POWER i TAKE-OFF STEP-UP DEVICE-4? T 25 TARGET msunc: DETERMINERS 24' TELESCOPE PATENTEDAPR 1 71w 3; 727, 514

DIVERGENCE DETECTORS MULTIPLIER INTEGRATOR 6 13 nsoucms GEAR l. an u SYNCHO-GENERATOR 3 9 10 11 12 g!) l SYNC RONOUS Kan. ,7 l W UNIT I I 9 P M l i TKEE SI F 16 I B n MECHANICAL E/l 5 INTEGRATOR DEVICE I l I 25 J TELESCOPE 24 Mam DETECTOR TURRET 17 k l l I I 1 MEANS FOR CONTROLLING THE FIRING OF A GUN AGAINST A MOVABLE TARGET BACKGROUND OF THE INVENTION The present invention relates to a method of controlling the firing of guns against movable targets and has specific reference to a device for carrying out this method which is designed more particularly for equipping tanks and like vehicles.

It is known that the quality of the control of gun firing against a moving target is measured by the probability of successfully hitting the target from the very first firing. This quality is essentially subordinate to the proper determination of the kinematic parameters of the target, that is, its distance or range and its speed. In fact, to get a direct hit on a target travelling at a distance D from the gun and an angular speed 9, the gun must be pointed ahead of the target with an angular shift or lead correction equal to the product (I T, wherein T is the time required for the projectile to travel along the distance D.

When the firing is controlled by aiming the target through a sighting telescope it is known to cause the movement of the gun, of a missile or rocket launcher or a mounting carrying at least one projectile launching gear, to be responsive to the movement of the sighting telescope through which the gunner pursues the target. Many known devices provide this servo action. It is also known to determine the distance of the target and to utilize this distance for adjusting the tangent-scale of the gun and calculate the time required for the projectile, missile or shell to hit the target. When the gunner has all these elements, hemust correct the firing as a function of the speed and distance of the target, before controlling the firing proper.

SUMMARY OF THE INVENTION In order to avoid this inconvenience, it is a first object of the present invention to provide a method of and means for controlling the firing of a gun equipped with a sighting telescope, whereby the correction corresponding to the distance and speed of the target can be determined and introduced into the firing process, the only operation developed to the gunner consisting in aligning the cross-hairs of the sighting telescope and the target.

To this end the method of controlling the firing of guns against movable targets, which consists in following or tracking the target through a sighting telescope, causing the gun movement to be responsive to the movement of the sighting telescope, measuring the distance to the target and producing from this measurement a first signal corresponding to the trajectory time or projectile course time necessary for the projectile to hit the target, is characterized in that it consists, in addition to the steps measuring the angular speed of the gun pursuing the target and producing therefrom a second signal in multiplying this second signal corresponding to the angular speed of the gun by said first signal corresponding to the trajectory or course time in order to obtain a corrector signal corresponding to the necessary firing correction or lead, and utilizing this corrector signal for controlling and moving the cross hairs of the sighting telescope in a direction opposite to the pursuing direction to an extent corresponding to said firing correction.

This method is advantageously applicable both to a gun mounted on a movable or swivelling turret and to a gun having its mounting fixedly anchored to a tank frame structure. In the first instance, the angular speed of the gun can easily be determined by measuring the angular speed of the swivelling turret, and in the other case this angular speed can be determined by measuring the angular speed of the complete tank structure, for example by using a gyroscopic platform. Moreover, this method is applicable not only for determining the directional correction but also for determining the gradient'or vertical correction, in case the target has a vertical speed component.

The firing correction obtained by using the method of this invention can be introduced into the sighting telescope in two different ways. A first way'consists in utilizing a sighting telescope having a single pair of movable cross-hairs constantly responsive to said correction signal and in this case when the firer has stabilized his pursuit, that is, when he has succeeded in aligning the cross-hairs with the target, the correction is introduced automatically and the firer can then fire or launch the weapon.

Another 'way of introducing the firing correction consists in utilizing a sighting telescope having two pairs of cross-hairs, one fixed and disposed centrally of the telescope field, the other movable and constantly being moved to an extent corresponding to the firing correction. In this last instance the gunner follows the target by using the fixed cross-hairs and when the tracking is stabilized the gunner locks the movable crosshairs and can fire the weapon after simply so training the turret that the thus locked cross-hairs has its center coincident with the target. This process introduces a correction only at the last moment and is advantageous in that it permits keeping the gun and the instruments associated therewith (range finder, searchlights, etc...) in the direction of the target during the entire tracking.

BRIEF DESCRIPTION OF THE DRAWING Other objects, features and advantages of this invention will appear more clearly as the following detailed description of a preferred form of embodiment of this invention, given by way of illustration, proceeds with reference to the accompanying drawing, in which:

FIG. 1 is a block diagram for explaining the operation ofa device designed for carrying out the method of this invention; and,

FIG. 2 is a diagram showing a typical form of embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Reference will firstly be made to FIG. 1 to describe the basic principle on which the firing correction determination method of this invention is based.

The gunner pursuing the target through his sighting telescope causes the gun axis to move at a speed 9 equal to the angular speed of the target. The angle of rotation of the gun is therefore that is, written as a Laplaces equation, ml; (Q/p) (p being Laplaces operator).

By using a multiplier 1, the angle III is multiplied by the trajectory time T. Thus, a quantity ill (QT/P) is available. By using a suitable servo device of which the diagram is illustrated in FIG. 1 and which comprises two divergence detectors 2 and 3, an amplifier 4, a motor 5 and an integrator 6, the cross-hairs of the sighting telescope are displaced by a quantity FD. T. In fact, if we disregard the time constant of amplifier 4 and motor 5, the transfer function of the servo-action system will be:

The value towards which 01 tends when the input {11 corresponds to a predetermined or given value D T can be calculated. Converted into Laplaces equation we thus have r11, (Q T /p It is known that the value towards which 0: tends when the time tends to infinity (permanent servo action condition) is equal to the value pa when p tends towards 0.

from which we have:

In fact, when p tends towards 0, pa tends towards Q,,T,,. With the servo action contemplated herein, with a speed 0 and a trajectory time T, the angular movement of the cross-hairs will actually be 9- T, which is the desired result.

This process is applicable to the determination of both directional and vertical corrections, for example in the case of a target having a vertical speed component.

Under these conditions, when carrying out the method of this invention, the cross-hairs of the sighting telescope can be corrected either for direction (horizontally) or for altitude (vertically), or even simultaneously for both cases.

Now reference will be made ot FIG. 2 to describe a typical form of embodiment of the present invention in the case of a gun mounted on a movable or swivelling turret, and in case only the direction correction is exerted on the cross-hairs of the sighting telescope.

As already known in the art of controlling the firing of a gun by optical sighting through a telescope 20, the angular movement of the tank turret 21 and therefore of the gun axis is responsive to the angular movement of the sighting telescope through which the firer follows his target. The members capable of causing the gun movement to be responsive to the movement of the sighting telescope may be designed and constructed in different known manners and therefore are no part of the instant invention. These members or servo-means are not described herein. By way of example, they comprise means 22 for detecting the direction of the sighting telescope (potentiometers, power take-off, etc..) of which the output signal is used for controlling a servo-mechanism 23 controlling in turn the members driving the turret 21.

Similarly, the members 24 and for determining respectively the target distance D, from this measurement, the time T required for the shell or projectile to travel this distance shell course time, are not described in detail since they are well known in the art.

In the device illustrated in FIG. 2, a power take-off 7, for example a gear engaging the toothed annulus of the tank turret, is provided. The output shaft of this power take-off 7 revolves at a speed K Q proportional to the angular speed of the turret, and therefore to the speed of the gun tracking the target. This output shaft drives the rotary plate of a ball-type step-up mechanism or like device 8 wherein the balls are shifted through a distance proportional to the shell course time T. The output shaft of this ball-type step-up device 8 will thus rotate at a speed K QT proportional to the firing correction to be made for controlling through a servo-action system to be described presently the movement, within the sighting telescope 20, of the cross-hairs 17 of this telescope, this movement taking place in a direction opposite to the pursuit movement with an amplitude corresponding to the necessary firing correction or lead.

The servo-action system may be designed as follows. The output shaft of the ball step-up device 8 drives the rotor of a synchro-generator 9 having its stator windings electrically connected to the stator windings of a synchro-motor 10. The synchro-generator 9 and synchro-motor 10 constitute together a so-called Selsyn motor. The output voltage of the synchro-moto'r l0, taken across the terminals of its rotor windings, controls through the medium of an amplifier 11 a motor-generator-reducing unit 12. The output shaft of this unit 12 controls on the one hand through the medium of a reducing gear 13 the stator of the synchromotor 10 which stator constitutes one of the divergence detectors designated by the reference numeral 3 in FIG. 1, and on the other hand, through the medium of a screw and nut assembly 14, the movement of the cross-hairs 17 and the input of a mechanical integrator 15.

This integrator 15 consists of a ball-type step-up mechanism having its plate rotatably driven at a constant speed from a synchronous motor 16. The output shaft of said mechanical integrator 15 drives the rotor of the synchro-motor 10 which rotor constitutes the divergence detector denoted by the reference numeral 2 in FIG. 1. I

The values of coefficients K,,, K, (coefficientof reducing gear 13) and K (coefficient of amplifier 11) are so determined that, with due regard for the balltype step-up device 8 and lS, synchronous motor 16 and screw and nut assembly 14, the angular movement of cross-hairs 17 be exactly equal to the above-defined product (I T.

In practice, the elements'7, 8 and 9 are secured to the turret and the elements 10 to 16 inclusive are incorporated in the gunner's sighting telescope.

Thus, with the device operating according to the method of this invention, when the gunner follows the target with the sighting telescope, the gun is caused in a manner known per se to follow or pursue the target to the same extent as the sighting telescope, while at the same time on the one hand the shell course time T is also determined in a manner known per se and, on the other hand, the device according to this invention determines the angular speed by the projectile course time in order to generate a lead or correction signal which is subsequently utilized for controlling, through the medium of the servo-action device, the cross-hairs of the sighting telescope. Therefore, in this case, the only operation to be performed by the gunner tracking his target consists in permanently aligning the crosshairs of his sighting telescope and the target, the firing correction being accomplished automatically by the device of this invention.

The firing correction previously determined by the above-described device may be introduced into the sighting telescope according to two different processes both capable of giving equivalent results during fields tests. In the first case, the sighting telescope comprises only a single pair of cross-hairs to which an angular movement depending on the firing correction to be made is constantly applied whereby, when the firer has stabilized his pursuit, that is, when the firer has succeeded in aligning the cross-hairs to the target, the firing correction takes place automatically, as already explained hereinabove, so that the only task devolved to the gunner consists in controlling the firing. In the second case, the sighting telescope comprises two pairs of cross-hairs: one pair is fixed and located centrally of the telescope field, and the other pair is movable and constantly moved by the device of this invention by an amount corresponding to the necessary firing correction. In this second case, the gunner tracks his target by means of the fixed cross-hairs and at the same time the device according to this invention moves the movable cross-hairs by an amount corresponding to said correction, and when the tracking is stabilized the gunner locks the movable cross-hairs by means of a suitable device so that he only has to train the turret until the locked cross-hairs are coincident with the target. As already explained hereinabove, this second method introduces the correction only at the last moment and therefore permits maintaining the gun and the devices associated therewith (range-finders, searchlights, etc..) pointed in the direction of the target through out the tracking period Although the present invention has been described hereinabove with reference to a gun mounted on a movable tank turret, it will be readily understood that it is also applicable to the firing control ofa gun mounted on the rigid frame structure of the tank, in which case the gun training being obtained by moving the tank as a whole. in this case the variations in the angular position of the gun may be detected by a suitable device, for example a gyroscopic platform having its output connected to the multiplier, instead of being detected by the power take-off 7.

On the other hand, although the above description refers mainly to a device capable of correcting the firing against a target moving horizontally or substantially horizontally, it will be readily appreciated that a similar device can be used for determining or introducing automatically into the sighting telescope the firing correction to be performed when the target has a vertical speed component. This device may advantageously be used for controlling the firing of anti-aircraft guns.

Moreover, in case the target were expected to have both horizontal and transverse speed components with respect to the gun, and also a vertical speed component, a device capable of imparting to the cross-hairs of the sighting telescope on the one hand a horizontal movement subordinate to the horizontal speed component of the target and on the other hand a vertical movement depending on the vertical speed component of said target may be contemplated without departing from the scope of the invention. This can easily be obtained by providing for each horizontal and vertical component, respectively, a device of the type described hereinabove and capable of moving the cross-hairs horizontally or vertically.

Furthermore, although the term gun" is used in the foregoing to denote the weapon of which the firing is to be controlled by applying the method and means of the present invention, it will be readily understood by anybody conversant with the art that this invention is also applicable to weapon launching devices, notably rocket launchers, and to any other projectile launchers.

Finally, it will be readily understood that many modifications and variations may be brought to the above-described form of embodiment without departing from the spirit and scope of this invention, since this specific form of embodiment is given by way of example only.

What we claim is:

l. A fire control system for laying a weapon on a moving target comprising, a movable telescope means for tracking a moving target, said telescope having movable cross-hairs, first servo means for effecting movement of a weapon responsive to the movement of said telescope means, first detection means for estimating the distance to said target, determining means for determining the timing of a projectile from said weapon, the input of said determining means being connected to the output of said first detection means, second detection means for measuring the angular train velocity of the weapon, a step-up device having two outputs connected respectively to the output of said second detection means and to the output of said determining means, second servo means having an input and output connected respectively to the output of said step-up device and the movable cross-hairs of said sighting telescope means, said second servo means comprising two divergence detectors connected to each other, a first input of the first divergence detector being connected to the output of said step-up device, an amplifier having its input connected to the output of said second divergence detector, driving means having an input connected to the output of said amplifier and the output connected to a second input of said divergence detector, an integrator having its input and output connected to the output of said driving means and to a second input of said first divergence detector respectively, means connecting said movable crosshairs of said sighting telescope to the output of said driving means in order to move said movable crosshairs by an amount equal to a necessary lead firing correction.

2. A fire control system for laying a weapon on a moving target according to claim 1, in which said stepup device consists of a first ball-type step-up mechanism having a rotary plate responsive to said second detection means and balls movable in proportion to the projectile course time in response to the output of said first step-up device connected to said first input of said first divergence detector, and said integraand a synchro-motor having stator windings electrically connected, said synchro-motor having a rotor winding connected to the input of said amplifier, said ball-type devices having output shafts, said rotors of said synchro-generator and said synchro motor being connected respectively to the output shafts of said first and second ball-type step-up devices, and the stator of said synchro-motor being connected to the output of said driving means. 

1. A fire control system for laying a weapon on a moving target comprising, a movable telescope means for tracking a moving target, said telescope having movable cross-hairs, first servo means for effecting movement of a weapon responsive to the movement of said telescope means, first detection means for estimating the distance to said target, determining means for determining the timing of a projectile from said weapon, the input of said deTermining means being connected to the output of said first detection means, second detection means for measuring the angular train velocity of the weapon, a step-up device having two outputs connected respectively to the output of said second detection means and to the output of said determining means, second servo means having an input and output connected respectively to the output of said step-up device and the movable cross-hairs of said sighting telescope means, said second servo means comprising two divergence detectors connected to each other, a first input of the first divergence detector being connected to the output of said step-up device, an amplifier having its input connected to the output of said second divergence detector, driving means having an input connected to the output of said amplifier and the output connected to a second input of said divergence detector, an integrator having its input and output connected to the output of said driving means and to a second input of said first divergence detector respectively, means connecting said movable cross-hairs of said sighting telescope to the output of said driving means in order to move said movable cross-hairs by an amount equal to a necessary lead firing correction.
 2. A fire control system for laying a weapon on a moving target according to claim 1, in which said step-up device consists of a first ball-type step-up mechanism having a rotary plate responsive to said second detection means and balls movable in proportion to the projectile course time in response to the output of said first step-up device connected to said first input of said first divergence detector, and said integrator consisting of a second ball-type step-up mechanism having a rotary plate driven at a constant speed, a synchronous motor driving said rotary plate, said integrator having balls movable in response to the output of said driving means, and the output of said driving means, and the output of said second ball-type step-up mechanism being connected to the second input of said second divergence detector.
 3. A fire control system for laying a weapon on a moving target according to claim 1, in which said two divergence detectors consist of a synchro-generator and a synchro-motor having stator windings electrically connected, said synchro-motor having a rotor winding connected to the input of said amplifier, said ball-type devices having output shafts, said rotors of said synchro-generator and said synchro motor being connected respectively to the output shafts of said first and second ball-type step-up devices, and the stator of said synchro-motor being connected to the output of said driving means. 